Hydraulic Press

Hydraulic press works on the basis of Pascal’s law (intensity of pressure at a point in a fluid

at rest is the same in all the directions). It is a machine that makes use of the pressure exerted

on a fluid section at another section to do a work. A schematic representation of the same is

provided below.

(http://www.hydraulicmania.com/hydraulic_press.htm)

The principle application of the system can be demonstrated with the problem blow.

Question 1:

A hydraulic press has a ram of 30 cm diameter and a plunger of 4 cm diameter. Find the mass

lifted by the hydraulic press when a force applied at the plunger by placing a 30 kg mass on

it.

Diameter of ram, D = 0.3 m

Diameter of plunger, d = 0.04 m

Force on plunger, FP = mass×g = 30×9.81 = 294.3 N

Area of ram, AR = (π/4)D2 = 0.07068 m

2

Area of plunger, AP = (π/4)d2 = 0.00126 m

2

Pressure intensity at plunger = FP/AP = 2,33,571.43 Pa

By Pascal’s law, the same pressure intensity would act at the ram, in all directions. Hence, to

find the force on the ram,

Force acting on Ram, FR = P×AR = 16508.83 N

Hence, mass that can be lifted with the ram = FR/g = 1,682.86 kg